Diversity and nitrogen removal efficiency of culturable aerobic denitrifying bacteria in the sediment and water in Dianchi Lake

Abstract:

[Objective] At present, nitrogen pollution has been becoming an important factor in water pollution. In order to unveil the diversity of culturable aerobic denitrifying bacteria in Dianchi Lake and obtain efficient aerobic denitrifying bacteria for providing evidence to bioremediate the polluted water or shallow groundwater. [Methods] Aerobic denitrifying bacteria were obtained through enrichment method and screening processes. The taxonomic positions of these aerobic denitrifying bacteria were analyzed based on 16S rRNA gene sequence comparisons. The efficient aerobic denitrifying bacteria were screened out by detecting nitrogen removal efficiency. [Results] In this study, 260 strains of aerobic denitrifying bacteria were isolated from the sediment and water samples of Dianchi Lake. These bacteria were classified into 59 species, belonging to 14 genera of 13 families of in 2 phyla of bacteria. Pseudomonas composed the major culturable aerobic denitrifying bacteria of Dianchi Lake,followed by Acinetobacter,Aeromonas and Delftia. Twelve strains with perfect nitrogen removal characteristics were screened out. Therein, 8 strains were identified as Pseudomonas spp. and 4 strains were identified as Acinetobacter spp. One efficient denitrifying strain N15-6-1 was screened out by using the quantitative analysis. Its nitrate and total nitrogen removal rates reached 98.81% and 96.27% in 48 h at 30-35℃, C/N=12, repectively. [Conclusion] From all the results, the higher diversity of culturable aerobic denitrifying bacteria inhabited in Dianchi Lake, which enriched the species resources of aerobic denitrifying bacteria, and furthermore, the efficient aerobic denitrifying bacteria provided a significant candidate strains to bioremediate the polluted water or shallow groundwater.

Key words:Dianchi lake;enrichment;aerobic denitrifying bacteria;phylogenetic analysis;nitrogen removal characteristic